Antonio Currao Department of Chemistry and Biochemistry ... · History of the Atlas of Zeolite...

Understanding Zeolite Frameworks

Antonio Currao

Department of Chemistry and BiochemistryUniversity of Bern

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Overview

What are Zeolites?� History� Classical and General Definition

� Channel and Pore Opening

� Synthesis� Application

Describing Zeolite Frameworks� International Zeolite Association (IZA)

� History of the Atlas of Zeolite Framework Types� Organisation of the Atlas

� Examples

How to Build Zeolites� Structural Sub-Unit (SSU)

� Periodic Building Unit (PPU)

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What are Zeolites?

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History

Zeolites have been studied by mineralogists for almost 250 years.

What are Zeolites?

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History

1756: A. F. Cronstedt� History of zeolites starts with the discovery of Stilbite.� Described behavior under fast heating conditions. The mineral

seemed to boil because of the fast water loss.

What are Zeolites?

�� = zein = to boil

�� = lithos = stone

� ZEOLITE

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History

1784: Barthelemy Faujas de Saint-Fond� As a French Professor in geology he formulated a nice formalism

�� ogie ��

� In his honor, a well known zeolite is called Faujasite in 1842.

What are Zeolites?

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History

Until the early 1940’s attempts to synthesize zeolites were madeby mineralogists interested in the stability with other minerals.

Union Carbide pioneered the synthetic molecular sieve zeolite business, initiating research in 1948 on adsorption for purification, separation and catalysis.� 1950: Synthesis of pure Zeolite A and X.� 1953: Patent filed for Zeolite A and X.

� 1954: Final structure of Zeolite A and X.

� 1956: Zeolite X with high silica/alumina ratios � Zeolite Y.� 1956: Structure of Zeolite A published.

� 1958: Structure of Zeolite X published.

� 1959: Patent granted.

What are Zeolites?

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History

What are Zeolites?

(Published 1956 in J. Am. Chem. Soc.)

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History

What are Zeolites?

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Classical and General Definition

Classical: � Aluminosilicate open network of corner-sharing [AlO4]- and [SiO4]-

tetrahedra (Al, Si � T-atoms build framework).

� Charge of the framework is compensated by mono or divalent cations or protons within the cavities or channels.

� Exchange capability of cations.� Additional water molecules are present in the cavities.

General: � Three-dimensional framework of tetrahedrally coordinated T-atoms

with cavities or channels with the smallest opening larger than six T-atoms.

� T-atoms: Si, Al, P, As, Ga, Ge, B, Be, etc.

What are Zeolites?

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Channel and Pore Opening

Aluminosilicates :

Silicates :

Aluminophosphates :

Galliumphosphates :

Microporous materials :

Mesoporous materials :

Macroporous materials :

7.4 x 7.4 Å

8.1 x 8.2 Å

12.7 x 12.7 Å

4.0 x 13.2 Å

< 20 Å

20 – 500 Å

> 500 Å

What are Zeolites?

Faujasite

UTD-1F

VPI-5

Cloverite

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Synthesis

Natural zeolites� Volcanic origin (hot-spring, lava, sediments).� Natural zeolites have been found in many different countries.

Hydrothermal sol-gel synthesis� Acqueous solution under vapor pressure of the mixture.� Temperature range up to 300 °C.

� Structure directing agent as template (e.g. tetramethyl-ammonium).

� Template removal by thermal and oxidative decomposition.

High pressure hydrothermal synthesis� High pressure autoclave.

What are Zeolites?

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Synthesis, Examples

What are Zeolites?

Linde Type A

Silicalite

Linde X

AlPO-5

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Application, Examples

Purification of gaseous and liquid mixtures and solutions by sorption (activation by evacuation and heating).Reversible sorption capacity for water.Removal of odors and pollutants.Ion exchange.Softening of water for washing (substituted polyphospates).Removal of heavy metal ions in mine wastewater and radioactive fission products (Cs, Sr).Natural zeolites used for soil fertilizing purposes (Submit ions of potassium, ammonium, phosphate).Catalysis in petrochemical industries (conversion of organic molecules in liquid and gaseous phase).

What are Zeolites?

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Describing Zeolite Frameworks

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International Zeolite Association (IZA)

Catalysis Structure Synthesis

IZACommissions

Describing Frameworks

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International Zeolite Association (IZA)

Books from the Structure Commission


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Availability

Printed Version Electronic Version (pdf-Files)

www.elsevier.com www.iza-online.org


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History of the Atlas of Zeolite Framework Types

145Dec. 2003Web Edition

13320015th

9819964th

8519823rd

3819782nd

2719701st

Zeolite Frameworks

YearEdition


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History of the Atlas of Zeolite Framework Types

Change of name for the Atlas recommended by IUPAC in 2001

Old : Atlas of Zeolite Structure Types

New : Atlas of Zeolite Framework Types

- Structure: Implies both, the framework and extra-framework constituents.

- Framework: Corner-sharing network of tetrahedreally coordinated atoms.


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Organisation of the Atlas

Two pages in the Atlas for each framework type code

Left page

Framework Type Informations

� Framework type code

� Stereographic figure� Idealized cell constants� Coordination sequences

� Vertex symbols� Secondary building units

� Loop configurations of T-atoms� Framework description� Isotypic framework structures

� References

Right page

Type Material Informations

� Crystal chemical data

� Framework density� Channels (observed rings)� Stereographic figure (channels)


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Left Page

Framework Type Informations


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Framework Type Code

Previously called Structure Type Code.

Three capital letters (IUPAC Commission on Zeolite Nomenclature, 1978).

Usually derived from the name of the type materials (Appendix D in the Atlas).

For interrupted frameworks the 3-letter code is preceded by a hyphen (-).

For intergrown materials, the * denotes a framework of a hypothetical end member.


Code Abbreviated Name Full Name

� LTA Linde Type A Zeolite A (Linde Division, Union Carbide)� LTL Linde Type L Zeolite L (Linde Division, Union Carbide)� FAU Faujasite� MFI ZSM-5 (five) Zeolite Socony Mobil – five� -CLO Cloverite Four-leafed clover shaped pore opening� *BEA Zeolite Beta

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Framework Type Code

Codes are only assigned to established structures that satisfy the rules of the IZA Structure Commission (Rules can be found in Appendix B).

The codes should not be confused or equated with actual materials. They only describe and define the framework.

Not allowed:� NaLTA, NaLTL, NaFAU

Correct is to use: | | for guest species, [ ] for framework host� |Na+

12(H2O)27|8 [Al12Si12O48]8-LTA or |Na| [Al-Si-O]-LTA

� |K+6Na+

3(H2O)21| [Al9Si27O72]-LTL or |K-Na| [Al-Si-O]-LTL

� |Na58| [Al58Si134O384]-FAU or |Na| [Al-Si-O]-FAU

Framework types do not depend on composition, distribution of the T-atoms, cell dimensions or symmetry (T-atoms: Si, Al, P, As, Ga, Ge, B, Be, etc.).


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LTA Framework: Stereographic Figure


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LTA: Structure and Framework Figures


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LTL Framework: Stereographic Figure


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LTL: Structure and Framework Figures


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Idealized Cell Parameters

They are obtained after geometry refinement in the highest possible symmetry for the framework type.

Refinement was carried out assuming:� Hypothetical SiO2 composition� dSi – O = 1.61 Å

� dO – O = 2.629 Å

� dSi – Si = 3.07 Å

a = 18.1 Åc = 7.6 Å

P6/mmmHexagonalLTL

a = 11.9 ÅPm-3mCubicLTA

Cell ParametersSpace GroupCrystal System


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Coordination Sequences (CS)

Each T-atom is connected to N1 = 4 neighboring T-atoms through oxygen bridges.

These neighboring T-atoms are then linked in the same manner to N2T-atoms in the next shell.

Each T-atom is counted only once.

Infinite, ideal case without T-atom sharing:

N0 = 1 N1 = 4 N2 = 12 N3 = 36 N4 = 108

Listed in the Atlas for every T-position: � Multiplicity and site symmetry of the position� CS from N1 up to N10


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Coordination Sequence for LTA

T1 (24, m) 4 9 17 28 42 60 81 105 132 162


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Coordination Sequences for LTL

T1 (24, 1) 4 9 17 29 46 69 … T2 (12, m) 4 10 21 35 49 66 …


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Vertex Symbols

The vertex symbol indicates the size of the smallest ring associated with each of the 6 angles of a tetrahedron (T-atom).

The symbols for opposite pairs of angles are grouped together.

Rings of the same size at a vertex are indicated by a subscript.

LTA T1 4 . 6 . 4 . 6 . 4 . 8

LTL T1 4 . 4 . 4 . 6 . 6 . 8T2 4 . 83 . 4 . 83 . 6 . 12


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Vertex Symbol for LTA

4 . 6 . 4 . 6 . 4 . 8


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Vertex Symbols for LTL

4 . 4 . 4 . 6 . 6 . 8 4 . 83 . 4 . 83 . 6 . 12


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Secondary Building Units (SBU)

The primary building unit is the TO4tetrahedra

SBU are derived assuming that the entire framework is made up of one type of SBU only.

Assemblage of the framework does not necessarily involve crystallographic symmetry operations.

If more than one SBU is possible, all are listed.

Number in ( ) = frequency of occurrence


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Secondary Building Units for LTA

8 or 4-4 or 6-2 or 4-2 or 4


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Secondary Building Units for LTL

8 or 6


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Loop Configuration of T-atoms

Simple graph showing how many 3- or 4-memberd rings a given T-atom is involved in.

Can be used for classification purposes.

Information given is a subset of the vertex symbol.

Solid lines: T – O – T link.

Dotted lines: T – O bond found in interrupted frameworks.

Number in ( ) = frequency of occurence


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Loop Configuration of T-atom for LTA


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Loop Configuration of T-Atoms for LTL


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Framework Description

For all 15 framework types of the so-called ABC-6-family the ABC stacking sequence is listed.

AFT

Listed are also some other structural relationship which are thought to be helpful.

FAU


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Isotypic Framework Structures

The type material, the species first used to establish the framework type, is given first and marked with an asterisk.

As-synthesized materials that have the same framework type but different chemical composition.

Materials with different laboratory code.

Materials obtained by post synthesis treatment (e.g. ion exchange, dealumination) are generally not included.

LTA LTL


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Zeolite Type Categories and Framework Type Groups

Zeolite type categories:� Silicates� Phosphates

Framework type groups:� Silicates

� Phosphates� Both, silicates and

phosphates


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References

Is not a complete list.

As general rule, references are given to:� Work to type of materials first establishing that framework type.

� Subsequent work adding significant information regarding the framework topology.

References to isotypes are limited to the work in which sufficient data are provided to establish the identity.


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Right Page

Type Material Informations


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Crystal Chemical Data

Composition, expressed in terms of cell contents (New IUPAC rules are used).

Crystal system, space group and cell parameters.

Relationship of the unit cell orientation with respect to the framework type, if the space group setting of the type material differs from that of the framework type.


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Framework Density (FD)

The framework density is a simple criterion for distinguishing zeolites and zeolite-like materials from denser materials.

Definition:

Non-zeolitic, denser framework structures: FD > 21.

Zeolite with fully crosslinked frameworks: FD = 12.1 – 20.6.

FD’s less than 12 have only been encountered for the interruptedframework of cloverite (-CLO).

The FD is obviously related to the pore volume but does not reflect the size of the pore openings.

3 Å1000Atoms-T of Number


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FD vs. Smallest Ring in Loop Configuration

The + sign indicates that there are some T-positions associated with only larger rings

LTA� Smallest ring size: 4

� FD = 12.9

LTL� Smallest ring size: 4� FD = 16.3

MFI� Smallest ring size: 4+� FD = 17.9


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Channels

Short notation for description of channels

Channel direction, relative to the axis of the type material structure:� <. . .> : All symmetry related directions.� [. . .] : Only given direction.� ⊥[. . .] : Channel direction is at right angle to the given direction.

Number of T-atoms forming the ring (in bold type).

Free diameters of the channels in Å.

Number of asterisks (*): Channel is one- two- or three-dimensional.

Double arrow (↔): Interconnecting channel systems.

A vertical bar ( | ): No direct access frome one channel system to the other.


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LTA: Channel

<1 0 0> 8 4.1 x 4.1 ***


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LTL: Channel

[0 0 1] 12 7.1 x 7.1 *


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OFF (Offretite): Channels

[0 0 1] 12 6.7 x 6.8 * ↔ ⊥[0 0 1] 8 3.6 x 4.9 **


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RHO (Zeolite Rho): Channels

<1 0 0> 8 3.6 x 3.6 *** | <1 0 0> 8 3.6 x 3.6 ***


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How to Build Zeolites

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Building Units

Zeolite frameworks can be thought to consist of finite and infinitecomponent units.

Finite units indroduced are:� Secondary Building Unit (SBU)� Structural Sub-Unit (SSU)

Infinite units can be build up by different finite building units:� Periodic Building Unit (PBU)

Component units, finite or infinite, are used to build the framework using translation, rotation, or mirroring.

Building units are common to several framework types and allow an easy description of the framework.


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Structural Sub-Unit (SSU)

SSU have greater complexity than SBU, e.g. polyhedral cages.

SSU are not SBU because very often the framwork can not be constructed from SSU alone.

Frequently, SSU need to share corners, edges or faces to complete the framework.

β-cage or sodalite cage (24 T-atoms)α-cage (48 T-atoms)


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Structural Sub-Unit for LTA

α-cage β-cage


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Structural Sub-Unit for LTA and RHO

LTA RHO


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PBU: Framework of EMT and FAU

EMT View along [1 1 0] FAU


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Periodic Building Unit for EMT and FAU


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PBU: Framework of EMT

Mirror symmetry between successive layers


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PBU: Framework of FAU

Inversion symmetry between successive layers


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PBU: Super Cage of FAU


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References

Ch. Bärlocher, W.M. Meier, D.H. Olson, Atlas of Zeolite Framework Types, 5th

rev. Ed., Elsevier, Amsterdam, 2001.

H. Ghobarkar, O. Schläf, U. Guth, Zeolites – from Kitchen to Space, Prog. Solid. St. Chem. 1999, 27, 29 – 73.

Zeolite Synthesis, ACS Symposium Series 398, M.L. Occelli and H.E. Robson Editors, ACS, Washington, 1989.

R.M. Barrer, Hydrothermal Chemistry of Zeolites, Academic Press, London, 1982.

R.M. Barrer, Zeolites and Clay Minerals as Sorbents and Molcular Sieves, Academic Press, London, 1978.

D.W. Breck, W.G. Eversole, R.M. Milton, T.B. Reed, T.L. Thomas, J. Am. Chem. Soc. 1956, 78, 5963 – 5971.

T.B. Reed, D.W. Breck, J. Am. Chem. Soc. 1956, 78, 5972 – 5977.

Antonio Currao Department of Chemistry and Biochemistry ... · History of the Atlas of Zeolite...

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Transcript of Antonio Currao Department of Chemistry and Biochemistry ... · History of the Atlas of Zeolite...